oracle 用户密码过期后不允许修改密码

--本人是初学者，不知道还有没有更好的方法

create table PASSWD_CHANGED

(

  USER_NAME  VARCHAR2(20),

  OLD_PASSWD VARCHAR2(100),

  NEW_PASSWD VARCHAR2(100)

)

CREATE OR REPLACE FUNCTION my_password_verify(username     VARCHAR2,

                                              password     VARCHAR2,

                                              old_password VARCHAR2)

  RETURN BOOLEAN IS

  v_days NUMBER(20);

BEGIN

  EXECUTE IMMEDIATE 'SELECT  TRUNC(expiry_date)-TRUNC(SYSDATE) FROM DBA_USERS u  WHERE u.username=:username'

    INTO v_days

    USING username;

  IF v_days < 1 THEN

    raise_application_error(-20001, 'the password has expired!'||chr(10)||'Contact :13611111111');

  END IF;

  /*

  IF LENGTH(password) < 6 THEN

  raise_application_error(-20001,'Password must be at least 6 characters long');

  END IF;

  */

  INSERT INTO passwd_changed VALUES (username, old_password, password);

  RETURN(TRUE);

END;